This bacterial ooze may also be observed on young fruits or infected blossoms. In the spring, a cream or light yellow-colored liquid may ooze from the margins of the cankers. When the bark is removed from these cankers, there is a sharp line of distinction between white healthy wood and infected reddish-brown wood. The cankers enlarge slowly and may eventually girdle the limb. The cankers are often separated from healthy bark by narrow cracks. Infected fruit turn brown (apple) or black (pear) and eventually shrivel and become mummified.ĭark, sunken cankers usually form on the larger branches. Infected blossoms shrivel, and as infections move into the twigs, the leaves on the twigs wilt and turn brown. The first symptoms are usually observed following the blossoming period. The dead leaves remain attached to the twigs, giving the tree the appearance of having been scorched by fire hence the name “fire blight”. A characteristic symptom of terminal blight is the bending of the blighted terminal to resemble a “shepherd’s crook”. Symptoms include sudden wilting followed by shriveling and blackening of the blossoms and young shoots. Blossoms, twigs, leaves, and young fruit can all be infected. Credit: A.L.įire blight is most damaging during warm (70☏), humid weather. More information can be found in the Integrated Management Guide for Commercial Apples in the Southeast.įeatured image from Penn State Department of Plant Pathology & Environmental Microbiology Archives, Penn State University, Bugwood.Fire blight on apple shoot note Shepard’s crook at shoot tip. After each cut, clean all tools with a solution of isopropyl alcohol or other disinfectant to avoid spreading the bacteria. In fall or winter, prune the diseased wood 6 to 8 inches below the cankers. Growers should prune diseased wood approximately 12 to 14 inches below visible cankers during the growing season. If a tree is infected with fire blight, all diseased tissue (blighted twigs and branches) should be removed as soon as possible to slow the spread of the disease. Having improper practices that produce rank, succulent growth with increase the possibility of the disease developing. Beginning in late winter to early spring and continuing through the growing season, growers should remove all root sprouts and suckers from trees. Do not cultivate pear and apple orchards late in the season and do not severely prune susceptible cultivars. Growers should regulate plant growth and apply fertilizers so that moderate shoot growth is maintained. Having proper cultivation and fertilization management practices is key to prevention. Aside from planting resistant varieties, there are other steps grower should take to prevent this disease. The best way to reduce the chances of fire blight is to purchase varieties of apple and pear trees that have some resistance to the disease. Control OptionsĪ control program combining resistant varieties, sound cultural practices, sanitation, fertilization, and pesticides is needed to protect plants from fire blight. Badly diseased trees and shrubs are usually disfigured and may even be killed by fire blight. The term fire blight describes the blackened, burned appearance of damaged flowers, twigs, and foliage. Fire blight is a bacterial disease that affects apples, pears, and other fruit and ornamental plants.
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